Forcing ETH transfers to contracts that are not designed to receive them, due to the absence of a payable fallback or receive function, can lead to permanently locked funds within these recipient contracts. This situation, facilitated by low-level operations like selfdestruct, presents a significant severity issue that undermines the predictability and safety of smart contract interactions in the Ethereum ecosystem. To mitigate such risks, it is recommended that sending contracts verify the recipients ability to handle ETH in a standard manner and that developers design contracts with interoperability and safe ETH handling in mind, ensuring the broader reliability and trustworthiness of the ecosystem.
https://github.com/code-423n4/2024-03-coinbase/blob/main/src/MagicSpend/MagicSpend.sol#L158-L162
